1. Field of the Invention
The invention relates to an articulating device and method of manufacture thereof. In addition, the invention relates to the use of the articulating device for steering medical devices such as the distal portion of medical devices typically used in minimally invasive surgery.
2. Description of Related Art
Rigid instruments, which may, for example, be catheters, graspers, or other tools, limit the ability of the surgeon to access the interior portions of the body. By having articulateable distal portions this adds an extra degree of freedom, thus reducing the need for changing tools during a procedure, and as a result reducing the time needed for the procedure to the mutual benefit of surgeon and patient alike.
As already stated the majority of tools used in these procedures are rigid. There are a variety of devices which have a degree of steerability added via a fixed curve being introduced in the distal end, and some devices which have steerable tips. Examples of steerable tips can be found in commonly owned and copending application Ser. No. 07/903,587 and U.S. Pat. No. 4,934,340 ("Wendel"), and U.S. Pat. No. 5,114,403 ("Clarke"). In many of these devices the distal tip, on being articulated, suffers from a problem commonly described as "S-ing". This term refers to the tendency for the articulating portion of the device to take on an S-shape, in which it no longer lies in a single plane. This is particularly problematical in small diameter devices wherein it is not possible to add stiffening members to alleviate this. The current invention offers a means of producing small diameter devices which freely articulate but have no tendency to "S". Additionally, for the aforementioned types of surgical devices it is frequently highly desirable that the tip be able to support significant end loading in the bent (or articulated) state. Existing devices generally do not provide such strength.
Various devices are known for steering medical devices such as catheters. For instance, steering mechanisms are discussed in U.S. Pat. Nos. 4,353,358 ("Emerson"); 3,470,876 ("Barchilon") and 4,245,624 ("Komiya").
U.S. Pat. No. 4,353,358 ("Emerson") discloses a disposable sigmoidoscope having a tubular portion of plastic material wherein a free end is weakened by providing one or more cut-outs or notches or by making the side of the tubular portion thinner. An operator cord member of wire, plastic or string member is attached to the free end and extends along the outer surface of the segments between the cut-outs, on the inside of the segments or through the weakened side of the device. Pulling on the member allows the tubular member to be bent somewhat but not so much that the operator can no longer see through the passage through the tubular member. A protective outer layer or sheath covers the cut-outs in order to prevent discomfort to the patient during insertion and withdrawal of the device and prevent material from entering the device through the cut-outs.
U.S. Pat. No. 3,470,876 ("Barchilon") discloses a 1/8 to 2 inch diameter catheter including an outer tube, an inner tube and a rigid end piece connecting the distal ends of the inner and outer tubes. The end piece has a flange and four tensioning cords are attached thereto such that each cord is offset 90.degree. with respect to each other. The inner and outer tubes are of flexible material such as a silicone compound having a durometer of 48. The cords are of material such as wire or nylon and the catheter can be bent in any desired direction by pulling on one or more of the cords.
U.S. Pat. No. 4,245,624 ("Komiya") discloses an endoscope having an observation optical system, a flexible plastic guide tube and a wire, each of which is located in a respective one of three channels extending longitudinally through a distal end of the endoscope. The guide tube is movable longitudinally beyond the distal end of the endoscope and the wire is attached to a distal end of the guide tube for bending the guide tube. When the guide tube is empty, liquid can be sprayed from or sucked into the distal end thereof. On the other hand, a medical implement such as forceps can be inserted into the guide tube and the wire can be used to bend the guide tube and medical implement toward a prescribed location in a body cavity. The guide tube can be made more flexible by using a plastic material foamed at a progressively higher rate at the distal end thereof. Alternatively, the guide tube can be made thinner at the distal end thereof or the guide tube can be surrounded by a coil of plastic or metal which has a progressively larger pitch toward the distal end of the guide tube.
It would be desirable in the medical field to have a steering device which prevents S-ing and instead allows accurate uniplanar bending of a distal end of a medical device. It is further desirable that such a steering device be capable of sustaining significant end-loading forces in the articulated state.